As a conventional steering lock device for an automobile, one disclosed in W02006/092186 (Patent Document 1) is known. A configuration of this steering lock device 100 is shown in FIG. 17 to FIG. 19. The steering lock device 100 includes a lock member 103, a worm wheel 107, and a pin 108. The lock member 103 is urged toward a steering shaft 102 of an automobile by a coil spring 101, and capable of being engaged with the steering shaft 102. The worm wheel 107 is coupled with a motor 104 via a worm gear 105, and having a slope 106 spirally inclined along an axial direction. The pin 108 moves along the slope 106 along with rotation of the worm wheel 107.
The motor 104 is rotated to its lock direction when the automobile is parked, so that the worm wheel 107 is rotated its lock direction via the worm gear 105. The pin 108 slides along the slope 106 along with the rotation of the worm wheel 107, so that the lock member 103 shifts from its unlock position to its lock position. As a result, an end of the lock member 103 is engaged with the steering shaft 102 to prohibit rotation of the steering shaft 102, and thereby it is made impossible to drive the automobile.
After that, the motor 104 is rotated to its unlock direction, so that the worm wheel 107 is rotated its unlock direction via the worm gear 105. The pin 108 slides along the slope 106 along with the reverse rotation of the worm wheel 107, so that the lock member 103 shifts from its lock position to its unlock position. As a result, an engagement between the lock member 103 and the steering shaft 102 is released to enable the rotation of the steering shaft 102, and thereby the automobile is made possible to be steered.